The preparation of sulfonate ionomers by copolymerization techniques has been of considerable interest because of the favorable economics associated with such processes versus those associated with sulfonated polymers prepared by sulfonation of a preformed polymer backbone. In addition it is possible to arrive at structures by copolymerization that are not achievable by preformed polymer sulfonation, i.e., different backbones, different functional groups, etc. for the most part emulsion techniques have been utilized for the preparation of the copolymers, i.e., sodium styrene sulfonate, styrene; sodium styrene sulfonate, isoprene. Obtaining the copolymer in the form of an emulsion presents problems for many applications of the solid polymer. Isolation techniques can be expensive and awkward to perform. Emulsions from sulfonate ionomers are more stable and difficult to break than ordinary polymer emulsions. Suspension polymerization offers a route to obtain copolymer directly in a useful solid form as small beads resulting from an easily carried out process.
The differences between emulsion and suspension polymerizations involve the mechanism of the polymerization and the size and stability of the resulting polymer particles. It is sufficient to say that an emulsion polymerization yields particles in the size range of 0.05 to 2 .mu.M. These particles are colloidal in nature and in most cases require some external action in order to obtain flocculation and subsequent solid polymer isolation. On the other hand suspension polymerization yields large particles of 10-5000 .mu.M in size. These are suspended in the polymerization process by the use of suspending agents as well as by mechanical agitation. Polymer isolation can be accomplished by simple filtration techniques. Because of obvious coagulation problems the suspension technique is most often accomplished with plastic-like polymers, e.g., styrene, PVC.